rm extra line, english, mention timestamps ** Description changed:
I've noticed that `/sys/devices/system/cpu/vulnerabilities/gather_data_sampling` had the `Vulnerable` value despite keeping the system up-to-date. The mitigation - microcode is available but not in used. It seems that the issue might be + microcode is available but not used. It seems that the issue might be the way the operations are ordered during start-up: verdict on the mitigation is potentially made before the microcode is loaded (as far as I understand). In any case, I don't know why my system doesn't have the mitigation - enabled, as I would expect this to be taken care of by default during + enabled. I would expect this to be taken care of by default during security updates or setup. - ```bash grep -o 'microcode[^ ]* [^ ]*' /proc/cpuinfo | sort -u ``` reports: `microcode : 0xbe` - ```bash dmesg | grep -i microcode ``` - reports: + reports (notice the timestamps): ``` [ 0.466934] microcode: Current revision: 0x000000be [ 0.466942] microcode: Updated early from: 0x00000086 ``` while ```bash dmesg | grep -i -E 'gds|mitigat' ``` - reports + reports (notice the timestamps): ``` [ 0.083727] mitigations: Enabled attack vectors: user_kernel, user_user, guest_host, guest_guest, SMT mitigations: auto [ 0.083733] Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl [ 0.083735] Spectre V2 : Mitigation: Enhanced / Automatic IBRS [ 0.083737] ITS: Mitigation: Aligned branch/return thunks [ 0.083739] Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization [ 0.083747] Spectre V2 : mitigation: Enabling conditional Indirect Branch Prediction Barrier [ 0.083750] GDS: Vulnerable [ 0.083756] Spectre V2 : Spectre BHI mitigation: SW BHB clearing on syscall and VM exit ``` ```bash rdmsr -0 0x10a ``` outputs `000000000a005c6b` ```bash rdmsr -0 0x123 ``` outputs `0000000000000010` - $ sudo rdmsr -0 0x123 - 0000000000000010 - - - Let me know if you need more diagnostic listings, I'm happy to provide whatever's needed. + Let me know if you need more diagnostic listings, I'm happy to provide + whatever's needed. A LLM has provided the following temporary fix - using a systemd service: ``` # /etc/systemd/system/gds-reenable.service [Unit] Description=Re-enable Intel GDS mitigation After=multi-user.target [Service] Type=oneshot ExecStart=/usr/sbin/modprobe msr ExecStart=/usr/sbin/wrmsr -a 0x123 0 [Install] WantedBy=multi-user.target ``` I've checked also the effect of setting the value of the MSR 0x123 register to 0 using a program (source provided by the LLM) that makes many call to `_mm256_i32gather_epi32`. There is indeed a noticeable difference in time: ~29ns/call with the value `0` vs ~15ns with the value `0x10`, which I'm assuming is proof that the mitigation is enabled whenever the MSR 0x123 register is set to 0 (instead of 0x10). ** Description changed: I've noticed that `/sys/devices/system/cpu/vulnerabilities/gather_data_sampling` had the `Vulnerable` value despite keeping the system up-to-date. The mitigation microcode is available but not used. It seems that the issue might be the way the operations are ordered during start-up: verdict on the mitigation is potentially made before the microcode is loaded (as far as I understand). In any case, I don't know why my system doesn't have the mitigation enabled. I would expect this to be taken care of by default during security updates or setup. ```bash grep -o 'microcode[^ ]* [^ ]*' /proc/cpuinfo | sort -u ``` reports: `microcode : 0xbe` ```bash dmesg | grep -i microcode ``` reports (notice the timestamps): ``` [ 0.466934] microcode: Current revision: 0x000000be [ 0.466942] microcode: Updated early from: 0x00000086 ``` while ```bash dmesg | grep -i -E 'gds|mitigat' ``` reports (notice the timestamps): ``` [ 0.083727] mitigations: Enabled attack vectors: user_kernel, user_user, guest_host, guest_guest, SMT mitigations: auto [ 0.083733] Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl [ 0.083735] Spectre V2 : Mitigation: Enhanced / Automatic IBRS [ 0.083737] ITS: Mitigation: Aligned branch/return thunks [ 0.083739] Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization [ 0.083747] Spectre V2 : mitigation: Enabling conditional Indirect Branch Prediction Barrier [ 0.083750] GDS: Vulnerable [ 0.083756] Spectre V2 : Spectre BHI mitigation: SW BHB clearing on syscall and VM exit ``` ```bash rdmsr -0 0x10a ``` outputs `000000000a005c6b` ```bash rdmsr -0 0x123 ``` outputs `0000000000000010` Let me know if you need more diagnostic listings, I'm happy to provide whatever's needed. A LLM has provided the following temporary fix - using a systemd service: ``` # /etc/systemd/system/gds-reenable.service [Unit] Description=Re-enable Intel GDS mitigation After=multi-user.target [Service] Type=oneshot ExecStart=/usr/sbin/modprobe msr ExecStart=/usr/sbin/wrmsr -a 0x123 0 [Install] WantedBy=multi-user.target ``` - I've checked also the effect of setting the value of the MSR 0x123 + I've also checked the effect of setting the value of the MSR 0x123 register to 0 using a program (source provided by the LLM) that makes many call to `_mm256_i32gather_epi32`. There is indeed a noticeable difference in time: ~29ns/call with the value `0` vs ~15ns with the value `0x10`, which I'm assuming is proof that the mitigation is enabled whenever the MSR 0x123 register is set to 0 (instead of 0x10). ** Description changed: I've noticed that `/sys/devices/system/cpu/vulnerabilities/gather_data_sampling` had the `Vulnerable` value despite keeping the system up-to-date. The mitigation microcode is available but not used. It seems that the issue might be the way the operations are ordered during start-up: verdict on the mitigation is potentially made before the microcode is loaded (as far as I understand). In any case, I don't know why my system doesn't have the mitigation enabled. I would expect this to be taken care of by default during security updates or setup. ```bash grep -o 'microcode[^ ]* [^ ]*' /proc/cpuinfo | sort -u ``` reports: `microcode : 0xbe` ```bash dmesg | grep -i microcode ``` reports (notice the timestamps): ``` [ 0.466934] microcode: Current revision: 0x000000be [ 0.466942] microcode: Updated early from: 0x00000086 ``` while ```bash dmesg | grep -i -E 'gds|mitigat' ``` reports (notice the timestamps): ``` [ 0.083727] mitigations: Enabled attack vectors: user_kernel, user_user, guest_host, guest_guest, SMT mitigations: auto [ 0.083733] Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl [ 0.083735] Spectre V2 : Mitigation: Enhanced / Automatic IBRS [ 0.083737] ITS: Mitigation: Aligned branch/return thunks [ 0.083739] Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization [ 0.083747] Spectre V2 : mitigation: Enabling conditional Indirect Branch Prediction Barrier [ 0.083750] GDS: Vulnerable [ 0.083756] Spectre V2 : Spectre BHI mitigation: SW BHB clearing on syscall and VM exit ``` ```bash rdmsr -0 0x10a ``` outputs `000000000a005c6b` ```bash rdmsr -0 0x123 ``` outputs `0000000000000010` Let me know if you need more diagnostic listings, I'm happy to provide whatever's needed. A LLM has provided the following temporary fix - using a systemd service: ``` # /etc/systemd/system/gds-reenable.service [Unit] Description=Re-enable Intel GDS mitigation After=multi-user.target [Service] Type=oneshot ExecStart=/usr/sbin/modprobe msr ExecStart=/usr/sbin/wrmsr -a 0x123 0 [Install] WantedBy=multi-user.target ``` I've also checked the effect of setting the value of the MSR 0x123 - register to 0 using a program (source provided by the LLM) that makes - many call to `_mm256_i32gather_epi32`. There is indeed a noticeable + register to 0 using a C program (source provided by the LLM) that makes + many calls to `_mm256_i32gather_epi32`. There is indeed a noticeable difference in time: ~29ns/call with the value `0` vs ~15ns with the value `0x10`, which I'm assuming is proof that the mitigation is enabled whenever the MSR 0x123 register is set to 0 (instead of 0x10). -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2172675 Title: Boot ordering: GDS mitigation status set earlier than microcode is updated To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/2172675/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
